A train carrying several dozen Republican lawmakers including US House Speaker Paul Ryan collided with a garbage truck on Wednesday (Jan 31) in Virginia, killing one person and sending six others, including a congressman, to hospital, officials said.

The White House said no members of Congress were seriously injured, and that President Donald Trump had been briefed on the accident.

At least 300 people, including lawmakers, their families and staff, were aboard the train from Washington bound for a Republican policy retreat in West Virginia, House Republicans Sean Duffy and Michael Burgess told reporters.

The truck that was struck was carrying three people, one of whom was killed and another seriously injured, Senator Bill Cassidy, a licensed physician who helped attend to the injured, said on Twitter.

"There is one confirmed fatality and one serious injury. There are no serious injuries among members of Congress or their staff," White House press secretary Sarah Sanders said in a statement.

"Our thoughts and prayers are with everyone that has been affected by this incident."

Train operator Amtrak said two crew members and three passengers were transported to a local hospital with minor injuries, and that transportation safety officials were investigating at the scene of the accident in Crozet.

The engine, which according to lawmaker photographs was mangled in the crash, derailed, but the rest of the cars remained upright on the tracks, according to Amtrak.

Congressman Jason Lewis, a first-term Republican from Minnesota, was taken to a hospital to be checked for a concussion, his office said.

"Due to the impact of the collision and per standard concussion protocol, Lewis is going to be checked out at a local hospital," a Republican aide said.

Some members of Congress who are doctors tended to the injured until emergency responders arrived.

"Laura & I & multiple other physicians tended to the patients until EMTs showed up," Cassidy tweeted, referring to his wife and emergency medical technicians.

There were 3 people in the truck that was straddling the track and which the train hit. One is dead. One I am told is being transported but has minor injuries. One has serious injuries—please pray. Laura & I & multiple other physicians tended to the patients until EMTs showed up. https://t.co/qAmoofxakV

The accident quickly became a security concern for police and security personnel tasked with guarding members of Congress, as lawmakers jumped off the disabled train to aid the injured.

The US Capitol Police said it was on the scene and "working closely with partner law enforcement agencies in response to the incident."

Senator Jeff Flake described a chaotic scene along the train tracks, where he said he helped transport a badly injured man away from the truck, and watched emergency responders try but fail to revive the person who died.

"It was harsh, it threw everyone up in their seat," Flake told reporters of the impact.

Remarkably, the incident marked the second time in seven months that Flake acted as a first responder at a moment of tragedy.

Last June, Flake was among several Republicans at a congressional baseball game practice when a gunman opened fire on lawmakers. Colleague Steve Scalise was gravely wounded, and Flake ran to his aid once the shooter was down.

Dozens of Republican members of the House of Representatives and the Senate left Washington earlier on Wednesday, the morning after Trump delivered his maiden State of the Union speech before Congress.

They were bound for the historic Greenbrier resort in White Sulphur Springs, West Virginia, for their annual retreat. The event's organizers said the retreat "will proceed with an adjusted program," including a moment of prayer for those involved in the accident.

Top House Democrat Nancy Pelosi said she was "praying that all are well both on the train and off."